118 AIR MASS ANALYSIS 
Fronts and Aircraft Icing 
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CoLD FrRONTS.—This (Fig. 6) and the following cross-sections (Figs. 7-9) 
through fronts are based on the synoptic experience of analysts working for 
a large air line (T.W.A.), and are taken from a paper on situations for icing of 
aircraft by E. J. Minser (BULL., March, 1938, pp. 118-121), with his kind 
permission. These meteorologists obtain radioed reports from the pilots as 
they fly along, and thus acquire an unusually detailed knowledge of actual 
cloud and upper-air structures. Fig. 6 is semi-schematic but vividly illustrates 
what happens just ahead of an advancing cold front (Pc into Nprc) in a 
mountainous region: clouds with snow squalls (this is winter) over each 
range. Note the freezing-line (dashed), the frontal precipitation (first rain, 
then snow), and the surface map at left. (Temp. in °F, heights in thousands 
of feet, in this and following figures.) 
